#!/usr/bin/perl -w
use strict;
use Data::Dumper::Simple;

my %codes;

while (<DATA>) {
    chomp;
    my $foo = (split /:/, $_)[1];
    if (!$codes{$foo}) {
        $codes{$foo}++;
    }
}

print Dumper(%codes);

__DATA__
HIT: code2
HIT: code3
HIT: code1
HIT: code90
HIT: code2
HIT: code34
HIT: code90

##</code><code>##

%codes = (
           ' code90' => 1,
           ' code2' => 1,
           ' code3' => 1,
           ' code2 ' => 1,
           ' code1' => 1,
           ' code34' => 1
         );